perf: Optimize get_recursion_context() (09da9c81) · Commits · 戴 / test

"Look ma, no branches!" Signed-off-by:

kernel/events/internal.h

+6 −10

Original line number	Diff line number	Diff line
		@@ -205,16 +205,12 @@ DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)

		static inline int get_recursion_context(int *recursion)
		{
		int rctx;

		if (unlikely(in_nmi()))
		rctx = 3;
		else if (in_irq())
		rctx = 2;
		else if (in_serving_softirq())
		rctx = 1;
		else
		rctx = 0;
		unsigned int pc = preempt_count();
		unsigned char rctx = 0;

		rctx += !!(pc & (NMI_MASK));
		rctx += !!(pc & (NMI_MASK \| HARDIRQ_MASK));
		rctx += !!(pc & (NMI_MASK \| HARDIRQ_MASK \| SOFTIRQ_OFFSET));

		if (recursion[rctx])
		return -1;